The Branch With Two Ancient Scriptures

Indo-Iranian is the eastern branch of Indo-European and the largest by speaker count, taking in the Indo-Aryan languages of northern South Asia, the Iranian languages from Persian to Pashto and Kurdish, and the small Nuristani group. Its speakers descend from populations that moved south from the Central Asian steppe in the second millennium BCE, and the branch divided into Indic and Iranian at some point around or before that movement. Two of its oldest members are preserved because they were sacred.

Vedic Sanskrit survives in the Rigveda, transmitted orally with a precision that has few parallels anywhere: systems of recitation were devised specifically to make error detectable, and the text was carried for centuries in memory before it was written. Old Avestan survives in the Gathas attributed to Zarathustra, transmitted in the same way by a priesthood that eventually committed them to writing in an alphabet invented for the purpose. Both traditions preserved their texts precisely because the sound was held to matter, which is why a linguist has access to two archaic Indo-European languages in something close to their original form. Nuristani, the third and smallest division of the branch, is spoken in a corner of Afghanistan whose peoples kept a non-Islamic religion until the end of the nineteenth century, and its position between the Indic and Iranian groups is still argued over.